A growing body of research is pointing to an intriguing possibility: GLP-1 drugs, best known for treating obesity and diabetes, may also lower the risk of cancer. While the evidence on GLP-1 cancer risk remains correlative, several recent studies suggest these medications not only reverse the carcinogenic effects tied to obesity but may also carry additional anti-inflammatory properties that help suppress tumors.

A Major Theme at a Leading Oncology Meeting

The potential role of GLP-1 drugs in preventing or controlling cancer emerged as a prominent topic at last month’s American Society of Clinical Oncology (ASCO) meeting, one of the most influential gatherings in the field.

ASCO spotlighted four studies, some published in its affiliated Journal of Clinical Oncology. The most notable tracked the medical and prescription records of more than 10,000 patients with early-stage cancer and found that GLP-1s reduced risk across six of seven cancers, with four reaching statistically significant levels. The breakdown looked like this:

• Significant declines: breast, liver, colorectal, and non-small cell lung cancer
• Modest declines: kidney and prostate cancer
• Least affected: pancreatic cancer

What stood out was that the protective effects appeared across cancers broadly, not just those with a known link to obesity. In the case of non-small cell lung cancer, for instance, the rate of progression to Stage IV disease was 22.3% among patients not taking a GLP-1, compared with just 10% among those who were.

From Diabetes Treatment to Multipurpose Drug

GLP-1 medications were originally developed decades ago to treat diabetes by altering the hormonal signaling between the brain and gut, reducing hunger and slowing digestion. Because they act on such powerful metabolic levers, they have since proven useful against a widening range of conditions, including obesity, heart disease, and sleep apnea, with potential applications in addiction and now, possibly, cancer.

A Crucial Caveat: Correlation, Not Causation

Experts are quick to temper the excitement. The current data falls well short of proving that GLP-1s work as cancer treatments. As Dr. Julie Gralow, ASCO’s chief medical officer, explained, these analyses relied on retrospective medical databases that left out important nuances, such as patients’ other health conditions, exercise habits, or diets.

Still, Gralow noted that the findings align with what’s already known about obesity as a driver of roughly a dozen cancers, as well as the established importance of healthy living in both illness and recovery. The results, she said, fit into a broader body of knowledge about exercise and healthy lifestyles following a cancer diagnosis.

A Striking Result in Breast Cancer

One of the studies presented at the conference offered a particularly eye-catching finding. By matching mammogram images to a prescription database, researchers found that women between the ages of 45 and 80 who took GLP-1 drugs were 30% less likely to develop breast cancer.

Cancer risk generally declines when patients lose weight, whether through diet or bariatric surgery. But radiologist Elizabeth McDonald of the University of Pennsylvania, who co-authored the study, said the protective effect from GLP-1s appeared stronger than what weight loss alone would explain. In her words, the weight loss by itself didn’t account for the magnitude of the effect they observed.

So How Might It Work?

That gap is what has researchers digging deeper. McDonald suspects that as GLP-1 medications regulate hunger and digestion hormones, they may also activate other metabolic pathways, potentially reducing inflammation, a known driver of cancer.

New trials are now beginning to explore exactly how GLP-1s might influence factors like chronic inflammation and immunosuppression, both of which could contribute to cancer growth.

One such effort is being led by oncologist Coral Omene at the Rutgers Cancer Institute, who plans to follow 40 breast-cancer patients starting tirzepatide, a GLP-1 drug sold under the brand names Mounjaro and Zepbound. Omene intends to regularly measure blood samples, track changes in cancer markers, and biopsy participants’ abdominal fat cells every six months to observe how they respond in terms of hormones and inflammation. As treatment progresses, her team will also monitor how the patients’ immune cells behave.

The hope, Omene said, is that this kind of detailed tracking will yield a clearer understanding of how best to deploy GLP-1 drugs against cancer.

What It Means for Now

The picture emerging from this research is genuinely promising, but it remains early. The studies show association rather than proven cause and effect, and much work lies ahead before GLP-1s could be recommended specifically for cancer prevention or treatment. For the moment, the findings add to a compelling case that these drugs influence the body in ways extending far beyond weight loss, and they give scientists a rich set of questions to pursue.